Pure Blends Research Articles

Characterization of high-performance composite bricks fabricated from recycled HDPE/PS blends and brick powder

Abstract This study explores the feasibility and benefits of utilizing plastic waste in the production of construction materials, specifically composite bricks. The escalating accumulation of plastic waste poses significant environmental challenges, which necessitates innovative approaches for recycling and re-utilization to mitigate pollution and reduce landfill use. Our research focuses on the synthesis of bricks by incorporating high-density polyethylene (HDPE) and polystyrene (PS) with sand brick powder, utilizing a compatibilizer (SBS-g-MA) to enhance interfacial adhesion and mechanical integrity. The experimental methodology involved the preparation of composite materials through melt mixing, followed by molding to form brick specimens. These were analyzed for their mechanical properties, including tensile strength, Young’s modulus, and elongation at break, as well as thermal properties such as degradation temperature and crystallization behavior. Results showed that the inclusion of sand brick powder significantly enhances the thermal stability of the composites, as evidenced by the higher degradation temperatures observed. Specifically, the degradation temperature increased from 300.59 °C in pure HDPE/PS blends to 420.39 °C in composites with 7% brick powder, suggesting the formation of a protective barrier against thermal decomposition. Moreover, mechanical testing revealed that composites with up to 7% brick powder exhibited improved tensile strength and Young’s modulus compared to pure polymer blends.

Characterisation of a continuous blender: Impact of physical properties on mass holdup behaviour

Continuous blenders are a key unit operation in Continuous Direct Compaction, a route to solid oral dosage forms that is receiving significant interest. Mass holdup in these blenders is a crucial variable; understanding how it is influenced by material properties, equipment configuration and process settings is key. The present work evaluated a Gericke GCM-450 blender for range of outlet weir aperture geometries (angled or horizontal), material properties (pure components and blends) and process settings (throughput and impeller speed). Results show opposing mass holdup behaviour depending on weir choice, material density and flowability, likely linked to the propensity of the material to form an inclined powder surface that matches – or does not – the chosen weir geometry. The present work underscores the need for fundamental process phenomena understanding, especially when insight is sought for how blender performance varies across multiple dimensions (throughput, impeller speed, material properties) and discrete equipment choices (weir geometry).

Evaluating Engine Performance, Emissions, Noise, and Vibration: A Comparative Study of Diesel and Biodiesel Fuel Mixture

This study investigates the performance, emissions, noise, and vibration characteristics of a single-cylinder, air-cooled, four-stroke diesel engine running on pure diesel (D100) and biodiesel blends (B10: 90% diesel, 10% biodiesel; B20: 80% diesel, 20% biodiesel) at 1800 rpm, where the engine delivers maximum torque. Key metrics such as torque, power, brake specific fuel consumption (BSFC), exhaust gas temperature, noise, vibration, and emissions (CO, CO2, HC, O2, NOx, and smoke opacity) were analyzed. The findings indicate that B10 enhances torque, power output, and overall fuel efficiency, especially at low to medium loads, with a significant 17.54% reduction in BSFC compared to D100 at 40% engine load. Vibration levels generally increased with biodiesel addition, while B10 and B20 both reduced smoke opacity, with B20 having a more substantial effect. HC emissions decreased at idle with B10 but increased at higher loads, suggesting more complete combustion with potential thermal stress on engine components. Noise and vibration results were mixed; B20 reduced noise at higher loads but increased vibration. At 100% load, B20 decreased noise by 1.42% compared to D100. Despite benefits such as improved torque and reduced particulate emissions, biodiesel blends, particularly B20, led to increased NOx and CO2 emissions, emphasizing the need for further op-timization of blend formulations and emission control strategies. This study provides valuable insights into the tradeoffs and potential of biodiesel blends as sustainable diesel alternatives.

Investigation of the performance and emission effects of ammonia-borane as a B–N-based amine-borane adduct in gasoline engines

This study examined the impact of varying concentrations of ammonia-borane (AB) in gasoline on engine performance and emissions across different load conditions. Four fuel formulations were tested: pure gasoline (G100) and gasoline blends containing 10%, 15%, and 20% AB (AB10, AB15, AB20). Increased AB concentration resulted in higher brake-specific fuel consumption (BSFC). While exhaust gas temperatures were highest with G100 (730.9 °C at full load), the AB blends, particularly AB20, exhibited lower temperatures, with a maximum reduction of 13.8%. The AB20 blend demonstrated elevated BSFC and increased oxygen (O₂) emissions but significantly reduced carbon monoxide (CO) emissions, with up to an 88.2% decrease at full load. Nitrogen oxide (NOx) emissions were generally lower for all AB blends. The highest NOx value was measured with G100 fuel at full load, while the lowest NOx value was measured with AB10 fuel. Under these conditions, a 23% decrease in NOx value was observed with AB10 fuel compared to G100. The engine's thermal efficiency decreased with AB blends at all load levels compared to pure gasoline. Thermal efficiency decrease of 13.76%, 22.32%, and 30.88% occurred for AB10, AB15 and AB20, respectively compared to G100.Overall, incorporating AB in gasoline reduced thermal efficiency and led to a notable decrease in NOx, hydrocarbons (HC), and CO emissions.

Performance evaluation of VCR system with pure and various blends of R134a, R1234yf, and R1234ze (E) refrigerants

AbstractThe current small passenger car vapor compression refrigeration systems use high global warming potential (GWP) refrigerants causing the greenhouse gas effect. In the present work, the low GWP of two pure refrigerants, R1234yf and R1234ze (E), and 16 blends of R134a, R1234yf, and R1234ze (E) are analyzed numerically. The experiments were conducted with R134a refrigerant to validate the numerical results. The experiments were conducted at the compressor speed of 600–1500 rpm and the condensing air at 30–40°C, relative humidity of 85%, and velocity of 1–3 m/s. The simulation and experimental results for R134a are deviated by a minimum of 10% and a maximum of 15%. It is found that the latent heat of vaporization of the two refrigerant mixtures with 80% R134a–20% R1234yf and the three refrigerant blends of 50% R134a–10% R1234yf–40% R1234ze (E) are the highest among 16 combinations. The other blends show a moderate difference of latent heat with R134a, but for maximum cooling capacity, the blends with 80% R134a–20% R1234yf and 50% R134a–10% R1234yf–40% R1234ze (E) are found to be more suitable for practical applications.

Numerical analysis of spray characterization of blends of hydrous ethanol with diesel and biodiesel

The spray characteristics of a fuel greatly influence the combustion as it affects the formation of an air–fuel mixture, which directly impacts the performance and emissions of the engine. This study investigates the physical injection spray characteristics of biofuels to optimize the engine operating parameters for their effective utilization. For the analysis of the spray characteristics of pure diesel (D100), 80% diesel—20% biodiesel (D80B20), 80% diesel—10% biodiesel—10% pure ethanol (D80B10E10), and 80% diesel—10% biodiesel—10% hydrous ethanol (D80B10HE10) are investigated. Computational Fluid Dynamics (CFD) modeling of a constant volume chamber under non-evaporative conditions is performed to conduct numerical analysis. The chamber pressure of 2 and 2.5 MPa and nozzle injection diameter of 0.126 mm, 0.15 mm, and 0.2 mm are considered to conduct the simulations. The variation in spray penetration length is analyzed and discussed for the injection of different fuel blends at different initial conditions. It is observed from numerical results that the high-density fuel blend D80B20 has a penetration length of 10.695% and 15.805% higher than pure diesel and D80B10HE10 blends, respectively. For pure diesel, with an increase in nozzle diameter from 0.126 mm to 0.15 mm and 0.2 mm, the penetration length is increased by 20% and 32%, respectively, and with an increase in pressure from 2 MPa to 2.5 MPa, penetration length is decreased by 14.62%. From this study, it can be concluded that biofuels like biodiesel and hydrous ethanol can be used with diesel in blended form over pure ethanol. Compared to pure ethanol, hydrous ethanol gives cost benefits and better spray characteristics.

Morphology optimization via pre-aggregation and miscibility matching in PM6:L8-BO ternary organic solar cells.

To elucidate the mechanism by which pre-aggregation and miscibility matching govern the active layer morphology in non-fullerene organic solar cells, chloroform (CF) and o-xylene (OX) were used as solvents, while D18 and N2200 were incorporated as third components into the PM6:L8-BO system. The incorporation of D18 enhanced device performance, whereas the addition of N2200 reduced device performance. Based on surface energy analysis, the free energies of pure components and binary blends in different solvents were calculated, showing that the Gibbs free energies of D18, PM6 and L8-BO exhibited better pre-aggregation matching. Employing the melting point depression method, the Flory-Huggins interaction parameters of D18 : L8-BO (1 : 6) and N2200 : L8-BO (1 : 5) blends were calculated. The results revealed that the miscibility of the samples cast with CF was superior to those cast with OX. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) observations revealed that D18 could induce L8-BO to aggregate and crystallize to form a nanofiber architecture, leading to an optimized phase separation. Attributing to the desirable miscibility of D18 with L8-BO, the D18:L8-BO nanostructures could be dispersed within an amorphous PM6 matrix, forming a double-fibril network morphology that facilitated charge transfer and enhanced device performance. In contrast, N2200 was immiscible with L8-BO, which led to the formation of a suboptimal morphology exhibiting excessive aggregation or excessive dispersion, resulting in a deterioration in charge transfer and device performance. The investigation of pre-aggregation matching in solvents, and miscibility matching of the components could provide guidance for the rational selection of appropriate solvents and suitable third components towards high-performance ternary organic solar cells.

DESIGN AND NUMERICAL INVESTIGATIONS OF AN AFTERBURNER SYSTEM USING METHANE-HYDROGEN BLENDS

The gas turbine industry strongly committed to develop gas turbines operating with 100% hydrogen till 2030, such fully supporting the transformation of the European natural gas grid into a renewable-based energy system by overcoming technical challenges and ensuring that this transformation takes place swiftly. By extending the fuel capabilities of gas turbines to hydrogen, their role can become predominant in the energy transition period but also in long-term energy strategies. In combined cycle configuration (CCGT), gas turbines are already the cleanest form of thermal power generation. For the same amount of electricity generated, gas turbines running on natural gas emit 50% less CO2 emissions than coal-fired power plants. Mixing renewable gas (e.g., green hydrogen, biogas) with natural gas enables further reduction in net CO2 emissions. In this paper pure hydrogen and blends of hydrogen methane will be studied as fuel in order to predict the behavior of afterburner system with a new designed geometry.

Feasibility Evaluation and Numerical Simulation of Diesel–Diethyl Ether–2–Methoxy Ethyl Ether Blends Fueling in Stationary CI Engine

In many developed economies, the diesel engine is very important for transportation and farming. There is a lot of research being done in the field of renewable energy to replace conventional energy sources because of the major environmental issues and the rising expense of diesel. Diesel engine cannot be reinstate because of its efficient performance at higher power and reliability with alternative engines. Diesel engine emissions are very harmful to the atmosphere and human health. The main contaminants in diesel engines are smoke and NOx, which need to be effectively monitored. A numerous research is going on to diminish the emissions from CI engines by using some additives as well as the use of alternative fuels. This experimental inquiry was conducted to identify a suitable addition to lower exhaust emissions and improve CI engine performance. The trials used various mix ratios of pure diesel and blends of diesel and diethyl ether-2-methoxy ethyl ether. Mixing of 5% DEE and 5% MXEE with 90% diesel on volume basis (D90–DEE5–MXEE5) showed optimum results of emission and performance. Low exhaust emissions (HC 63.15%, CO 60.00%, and Smoke 18.29%) found to be substantial at peak loads and performance increase (decreasing in BSFC 5.00% and increasing in BTE 3.00%) were compared to mixture D90-DEE5-MXEE5 with diesel (at standard engine conditions). However, NOx rises (2.60%).

Comparing data driven soft independent class analogy (DD-SIMCA) and one class partial least square (OC-PLS) to authenticate sacha inchi (Plukenetia volubilis L.) oil using portable NIR spectrometer

Sacha Inchi (SI) oil is valuable due to high content of omega-3 and omega-6, which are important in human diet, thus being susceptible to adulteration. In this work, a low-cost and portable Near Infrared (NIR) spectrometer was used to authenticate pure sacha inchi oil from adulterated one with cheaper oils. Principal component analysis (PCA) was applied as screening technique and showed a good class separation between pure SI oil and blends, with significant impact of unsaturated fatty acids present in SI oil. Data Driven Soft Independent Class Analogy (DD-SIMCA) provided better results when compared to One Class Partial Least Square (OC-PLS) for data analysis. DD-SIMCA was implemented in rigorous approach, and it reached Sensitivity (SEN) = 89.8 % and Specificity (SPE) = 93 % using α = 0.05 and 4 PCs, while ordinary OC-PLS required 10 LVs to reach SEN = 87.8 % and SPE = 84.3 %, performing better than Gaussian radial basis function (GRBF-OCPLS) and partial robust M-regression (PRM) approaches. Results indicate that low-cost NIR spectrometer coupled to one-class classifiers could be used to authenticate pure SI oil.

Performance and emission characteristics of safflower oil biodiesel blended with nanoparticles and hydrogen on diesel engines of road and bridge machinery

Due to high usage and demand of fossil fuels, the search of alternative fuels is necessary to safeguard the natural resources. In this study, safflower oil, CeO2 nanoparticles and hydrogen blends are used in a direct ignition engine of road and bridge machinery to study the performance and emission properties of test fuels. Hydrogen was added along with nanoparticles on biofuel while conducting the tests. Hydrogen was supplied at a mass flow rate of 10 L per minute throughout the testing of road and bridge machineryignition engine. The results of the tests were used to compute the road and bridge machinery ignition engine performance and emission properties. In order to compare the various biodiesel blends all the tests were carried out between 1800 rpm and 2800 rpm. In addition to the pure diesel and biodiesel blends, these nanoparticles and hydrogen blended fuels enhances the performance. Brake-specific fuel consumption was reduced while power, torque, and thermal efficiency were all increased. Road and bridge machinery ignition engine torque increased by 6% and 5% for S10NH and S20NH test fuels due to addition of hydrogen and nanoparticles to the normal blend, respectively, as compared to blend without nanoparticles and hydrogen. Pure C100 had a BTE of 24%, while S10 and S20 had a BTE of 21.9 %and 21.3%, respectively at lower engine speed. Enriched biodiesel with nanoparticles and hydrogen reduces CO and CO2 emissions, as compared with pure diesel. The primary goal of lowering CO and CO2 emissions was achieved, although the NOx emission level increased marginally.

Kinetic model-based group contribution method for derived cetane number prediction of oxygenated fuel components and blends

A four-step autoignition model was used to derive an expression for the ignition delay (ID) measured in ignition quality testers (IQT) with the derived cetane number (DCN) determined from this ID using the ASTM D6890 standard correlation. The model predicts DCN for individual compounds and blends as a function of each compound's global initiation and net chain branching rate constants. Expressions for these values were determined assuming they could be related to the functional groups present in each compound. Measurement data for 125 compounds and 94 binary and ternary blends (including oxygenates: alcohols, aldehydes, esters, ethers, and ketones), from literature and from measurements performed in our lab, were used to obtain the dependence of the measured ignition delay on each functional group. The new kinetic model-based group contribution method was able to predict the ignition delay of both pure compounds and blends, with an average DCN error of 4.4 (19%) and 2.8 (11%), respectively. The blend model was also used to develop an ID mixing rule by incorporating existing IQT ignition delay data for each compound. Use of the mixing rule gave an average DCN error of 3.6 (16%) for blends. Both the blend model and mixing rule were found to be superior compared to standard linear by volume fraction or mole fraction mixing rules commonly used to estimate the DCN of mixtures.

Property Improvement of Polybutylene Succinate (PBS), Polyhydroxybutyrate (PHB), and Polylactic Acid (PLA) Films with PCL (Polycaprolactone) for Flexible Packaging Application

Nowadays, developing highly biodegradable polymer films for flexible packaging applications is one of many researchers' demanding and challenging tasks. Conventional plastics/polymers are still being extensively used, creating environmental pollution. Because most of the commercially available plastic products are marketed as biodegradable are not truly biodegradable and have several limitations for making flexible packaging films. The main objective of this work is to manufacture biodegradable polymer blends, with the best performance characteristics, for flexible packaging applications. The paper focused on improving the properties, i.e., tensile, barrier, and biodegradation properties, of commercially available polymers such as Polybutylene succinate (PBS), Polyhydroxybutyrate (PHB), and Polylactic acid (PLA) by blending with Polycaprolactone (PCL) for flexible packaging application. Polymer films of various compositions such as PBS-PCL, PHB-PCL, and PLA-PCL blends were fabricated by injection molding and hot pressing. The characterization analysis included analyzing polymer blends' tensile and water vapor barrier properties, as per ASTM D882-18 method and ASTM E96-16 method, respectively, following that biodegradation analysis in compost (ASTM D5338-15 method) and seawater medium (ASTM D6991-17 method) of the polymer blends, and analysis of PCL blends' effect. The research showed that compared to the pure polymer blends such as PBS, PHB, and PLA blends, polymer blends with 20% of PCL has increased tensile elongation by 26.3%, 68%, and 171%, respectively, and the water vapor barrier properties were increased by 28.3%, 26.8%, and 30.3%. the biodegradation rate in compost medium was increased by 21.9%, 6.4% and 21.2%, and the biodegradation rate in seawater medium was increased by 31%, 7.5%, and 16.6%, respectively, even though a slight decrease in tensile strength. In conclusion, the polymer blends with 20wt% of PCL provide overall improved of polymer properties.

A review study on the use of dimethyl ether in diesel engines: effects on CO2 emissions

Emissions from vehicles and other fuel combustion systems can alter the composition of the atmosphere and augment its capacity to absorb heat. These gases, which are effective at trapping heat, are known as greenhouse gases and include all gases found in vehicle emissions. Reducing the emissions of carbon dioxide (CO2) has become an urgent necessity around the world, and many countries have imposed limits on their CO2 output. Using biofuels in automotive engines is an effective way of reducing greenhouse gas emissions. The CO2 emissions emitted from the combustion of biofuels are absorbed as trees and plants grow. Biofuels can be used either as pure fuels or blended with conventional fuels. Most research has declared that the most effective way to reduce greenhouse emissions is the use of various biofuels. Therefore, it is essential to assess the outcomes of research regarding alternate fuels or fuel additives to determine their proper utilization. Using of diesel engines can also help reduce CO2 emissions as they emit less CO2 emissions than gasoline engines. This review study investigates the effects the using of dimethyl ether on CO2 emissions in diesel engines. The results showed that CO2 emissions decrease when using the pure DME and DME blends with diesel and LPG fuels due to the oxygen content and the lower carbon to hydrogen ratio of DME. The decrements in CO2 emissions for pure DME, diesel–DME blends and LPG–DME blend are about 5.2–18.3%, 3–41.6% and 10.6–16.4%, respectively.

At-Line Sampling and Characterization of Pyrolytic Vapors from Biomass Feedstock Blends Using SPME-GC/MS-PCA: Influence of Char on Fast Pyrolysis.

Solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) analysis was used for the at-line sampling of pyrolytic vapors produced during the fast pyrolysis of biomass. The pure and binary blends of switchgrass (SWG) and pine harvest residues (PT6) were used as biomass feedstocks. Sequential SPME sampling allowed for monitoring of changes in the pyrolysis vapors as char accumulated in the fluid bed. The relative concentration and composition of the pyrolysis vapors desorbed from the SPME fibers were investigated using GC-MS, and the resulting chromatograms were analyzed using principal component analysis (PCA) to compare the composition of the pyrolysis vapors over the course of the pyrolysis run. The chemical compositions of both carbohydrate and lignin fragments varied as the char builds up in the reactor bed. Fragments derived from cellulose and hemicelluloses included anhydrosugars, furans, and light-oxygenated compounds. Lignin fragments included methoxyphenols, phenolic ketones, aldehydes, and low-molecular-weight aromatics. The composition of the carbohydrate fragments changed more than those of the lignin fragments as the char built up in the fluid bed. This combination of SPME-GC/MS-PCA was a novel, easy, and effective method for measuring the composition and changes in the composition of pyrolysis vapors during the fast pyrolysis process. This work also highlighted the effect of char build-up on the composition of the overall pyrolysis vapors.

Butyl butyrate, Jet A-1 and their blends: Combustion performance in the swirl stabilized burner at different inlet air temperature

The limited sources of fossil fuels and pollutant emissions are the major challenges for the aviation industry. To meet the energy demand of the aviation industry, researchers have taken an interest in exploring new aviation fuels and biofuels may be potential candidates for alternative aviation fuels due to their favorable properties for combustion. The physical properties of butyl butyrate meet the criteria for other possible aviation fuels to some extent. Therefore, in the present study, the combustion characteristics of butyl butyrate, Jet A-1, and their blends (BB/Jet A-1 with 10%, 30%, and 50% volumetric loading of butyl butyrate) are investigated experimentally in a swirl-stabilized combustion test rig at non-preheated and pre-heated swirling air (373 and 473 K). For a comparative assessment, the theoretical power output is kept constant for all the fuel cases by suitably adjusting the fuel flow rates based on the lower heating value of the fuels. The temperatures at the combustor exit (representative of turbine inlet temperature) for two individual fuels and their blends appear to be comparable which indicates the similar thermal output at these operating conditions. The post-combustion emissions show that Jet A-1 produced higher NOx compared to that of butyl butyrate and the blends. The NOx emission increases with an increase in the swirling air temperature and this trend is consistent for all the fuels tested. Irrespective of preheating, pure butyl butyrate and blends exhibit significantly lower CO emissions compared to Jet A-1. Pre-heating seems to influence all the fuels similarly; however, pure butyl butyrate and its blends with Jet A-1 (particularly 50% case) outperform in terms of overall performance.

Determination of Carbonyls Compound, Ketones and Aldehydes Emissions from CI Diesel Engines Fueled with Pure Diesel/Diesel Methanol Blends

Quantitative and qualitative analyses of chemical species out of CI engine tailpipe emissions fueled with pure diesel and diesel methanol blends, trapped in dinitro phenylhydrazine (DNPH) solutions, were performed. The formed hydrazine was studied using high-performance liquid chromatography (HPLC) accompanied by a detector for ultraviolet (UV). A set of carbonyl-DNPH derivative standards was developed and compared with engine tailpipe gases produced by both fuel modes. An understanding of carbonyl chemical compounds such as formaldehyde, acetaldehyde, and acrolein (HCHO, CH3CHO, and H2 = CHCHO, respectively) is essential for researchers to know how these chemicals affect human health and the environment. In both fuel modes, acetaldehyde was the main combustible product 25 ppm followed by formaldehyde 17 ppm, croton aldehydes 16 ppm, acrolein 12 ppm, and iso-valerdyhyde 10 ppm. In addition to these species, only a few other chemical species were detected in the exhaust gas. According to this study, carbonyl compounds from blended fuel contribute 15–22% of pure diesel fuel emissions. As shown by the results, engine operating conditions and fuel mode have a strong impact on the total amount of carbonyls released by the engine. Engine performance was highly influenced by different fuel modes and engine speeds. Using pure diesel, the regulated emissions, HC, CO, and NOx, registered high concentrations at a lower speed (1500 rpm) and NOx presented with the highest concentration of 4 g/kWh followed by CO with 1 g/kWh and HC with 0.5 g/kWh.

Mapping established psychopathology scales onto the Hierarchical Taxonomy of Psychopathology (HiTOP).

The Hierarchical Taxonomy of Psychopathology (HiTOP) organizes phenotypes of mental disorder based on empirical covariation, offering a comprehensive organizational framework from narrow symptoms to broader patterns of psychopathology. We argue that established self-report measures of psychopathology from the pre-HiTOP era should be systematically integrated into HiTOP to foster cumulative research and further the understanding of psychopathology structure. Hence, in this study, we mapped 92 established psychopathology (sub)scales onto the current HiTOP working model using data from an extensive battery of self-report assessments that was completed by community participants and outpatients (N = 909). Content validity ratings of the item pool were used to select indicators for a bifactor-(S-1) model of the p factor and five HiTOP spectra (i.e., internalizing, thought disorder, detachment, disinhibited externalizing, and antagonistic externalizing). The content-based HiTOP scales were validated against personality disorder diagnoses as assessed by standardized interviews. We then located established scales within the taxonomy by estimating the extent to which scales reflected higher-level HiTOP dimensions. The analyses shed light on the location of established psychopathology scales in HiTOP, identifying pure markers and blends of HiTOP spectra, as well as pure markers of the p factor (i.e., scales assessing mentalizing impairment and suspiciousness/epistemic mistrust).

Turbulent flame speed and morphology of pure ammonia flames and blends with methane or hydrogen

Ammonia appears a promising hydrogen-energy carrier as well as a carbon-free fuel. However, there remain limited studies for ammonia combustion especially under turbulent conditions. To that end, using the spherically expanding flame configuration, the turbulent flame speeds of stoichiometric ammonia/air, ammonia/methane and ammonia/hydrogen were examined. The composition of blends studied are currently being investigated for gas turbine application and are evaluated at various turbulent intensities, covering different kinds of turbulent combustion regimes. Mie-scattering tomography was employed facilitating flame structure analysis. Results show that the flame propagation speed of ammonia/air increases exponentially with increasing hydrogen amount. It is less pronounced with increasing methane addition, analogous to the behavior displayed in the laminar regime. The turbulent to laminar flame speed ratio increases with turbulence intensity. However, smallest gains were observed at highest hydrogen content, presumably due to differences in the combustion regime, with the mixture located within the corrugated flamelet zone, with all other mixtures positioned within the thin reaction zone. A good correlation of the turbulent velocity based on the Karlovitz and Damköhler numbers is observable with the present dataset, as well as previous experimental measurements available in literature, suggesting that ammonia-based fuels may potentially be described following the usual turbulent combustion models. Flame morphology and stretch sensitivity analysis were conducted, revealing that flame curvature remains relatively similar for pure ammonia and ammonia-based mixtures. The wrinkling ratio is found to increase with both increasing ammonia fraction and turbulent intensity, in good agreement with measured increases in turbulent flame speed. On the other hand, in most cases, the flame stretch effect does not change significantly with increasing turbulence, whilst following a similar trend to that of the laminar Markstein length.

In depth thermokinetic investigation on Co-pyrolysis of low-rank coal and algae consortium blends over CeO2 loaded hydrotalcite (MgNiAl) catalyst

This study investigates the co-pyrolysis behavior of bituminous coal (100%BC), algae consortium (100%AC), and their blends at various blending ratios. The pure and coal-biomass blends were characterized using CHN-S, GCV, and FTIR analysis. Whereas, the co-pyrolysis of blends were performed in a TGA. The deviation between the experimental and calculated values of weight loss (WL%), the residue left (RL%), and the maximum rate of weight loss (wt%/min) was used to calculate the synergistic effects. Kinetic parameters were investigated using the Coats-Redfern integral method through eighteen (18) reaction mechanistic models. The activation energy (Ea) for 100%BC was 85.04 kJ/mol through the F3 model, whilst for 100%AC showed 78.22 kJ/mol using the D3 model. Thermodynamic parameters such as Enthalpy (∆H) and Gibbs free energy (∆G) showed positive values, while Entropy (∆S) was negative for each coal-biomass blend. The catalytic co-pyrolysis of the optimum blend (20BCE-80AC) was studied using CeO2 loaded MgNiAl (CeO2 @MNA) as a multifunctional catalyst. The increased WL% displayed a positive effect toward a higher yield of volatile matter. Ea of the optimum blend in co-pyrolysis was further reduced through catalytic co-pyrolysis and Ea in the first and second stages was 72.48 kJ/mol and 13.76 kJ/mol, while 3 wt% catalyst loading further reduced its Ea in both stages to 67.82 kJ/mol and 41.21 kJ/mol. The use of CeO2 @MNA at 3 wt% loading showed a reduction in the peak devolatilization temperature (Tp) of the optimum blend substantially increasing the reaction rate, and reducing the Ea required for the decomposition process.